A. James Clark School of Engineering

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    MECHANICAL DESIGN OF DEXTEROUS MANIPULATOR LINKS
    (2018) Carlsen, Christopher James; Akin, David L; Aerospace Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This paper explores the challenges of dense structure-electronics packaging, specifically for a structural and electronics upgrade to the Ranger Tele-robotic Shuttle Experiment (RTSX) manipulators at the University of Maryland (UMD). Long serial-link manipulators are popular in the space industry, where the need for a long reach and high manipulability outweighs the need for high tip stiffness. For larger systems with co-located electronics, such as those used to berth vehicles on orbit, electronics packaging is not inhibited by the diameter of the link body. As link diameter decreases, co-locating electronics in the manipulator becomes diffcult without adding external extensions to house them. In such densely packed bodies, the control electronics are so integrated with structure that electronics maintenance requires disassembly of primary structure.
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    Direct Observation of Amyloid Nucleation under Nanomechanical Stretching
    (2013) Varongchayakul, Nitinun; Seog, Joonil; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Self-assembly of amyloid nanofiber is associated with functional and pathological processes such as in neurodegenerative diseases. Despite intensive studies, stochastic nature of the process has made it difficult to elucidate molecular mechanisms for the key amyloid nucleation. Here, we investigated the amyloid nucleation of silk-elastin-like peptide (SELP) using time-lapse lateral force microscopy (LFM). By repeated scanning a single line on a SELP-coated mica surface, we observed sudden stepwise height increases, corresponds to nucleation of an amyloid fiber. The lateral force profiles followed either a worm-like chain model or an exponential function, suggesting that the atomic force microscopy (AFM) tip stretches a single or multiple SELP molecules along the scanning direction, serves as the template for further self-assembly perpendicular to the scan direction. Such mechanically induced nucleation of amyloid fibrils allows positional and directional control of amyloid assembly in vitro, which we demonstrate by generating single nanofibers at predetermined nucleation sites.